1. Field of the Invention
The present invention relates to variable resistors and, more particularly, is directed to a slide type variable resistor suitable for use as a volume controller.
2. Description of the Prior Art
A variable resistor is generally represented in the drawings by a resistor 1 and a slider 2, as shown in FIG. 1A. However, in a practical variable resistor, a conductive thin lead 3 for current collection is disposed along the main resistor 1, and the lead 3 and the resistor 1 are bridged by the slider 2 as shown in FIG. 1B.
The variable resistor for use as a volume controller is required, as is well known, to have a logarithmic resistance characteristic in resistance change thereof, and so the variable resistor having a so-called A-curve resistance characteristic is utilized for controlling the volume.
In order to realize the variable resistor having the non-linear resistance characteristic, the following two manufacturing methods have been proposed.
In the first method, resistors having different resistance values are printed many times.
In the second method, a trimming process of the resistor pattern is performed after the printing of the resistor.
However, the second method has the disadvantage such that many numbers of processings are required after the printing process of the resistor, thereby remarkably increasing the cost of the variable resistor.
In the first method, since the accuracy of the resistance characteristic depends on the accuracy of the printing of resistors, the resistance characteristic fluctuates for every variable resistor.
When two variable resistors having different resistance characteristics due to the fluctuation, for example, are interconnected with each other so as to be cooperated and used to control the volume of stereophonic sound, the position of a reproduced sound image disadvantageously fluctuates to the righthand or lefthand side.
A sound control console in a broadcasting station or the like employs a slide type variable resistor since the adjusting position can be visually recognized. In this case, if the resistance characteristic fluctuates at every variable resistor, a difference between an actual attenuation degree of the variable resistor and a scale of attenuation degree thereof on the sound control console will disadvantageously fluctuate for every variable resistor.
In particular, when the variable resistors having different resistor characteristics are employed in a multi-channel mixer, many adjusting levers interlinked with the sliders of the resistors, which are to be arranged in a linear line, are arranged in a zigzag fashion. Thus, in this case, the adjustment of volume may be seen to be erroneous for an operator.